Coating for assembly of parts

ABSTRACT

Metal carbonitride coatings are deposited on assemblies, the parts of which are connected by an adherent material by first heating a selected assembly, including the adherent material, and subsequently contacting the assembly with a gaseous stream which will yield reactive hydrogen, nitrogen, carbon, and a selected metal, upon contact with the heated assembly. The gaseous stream may, for example, contain hydrogen, nitrogen, titanium tetrachloride, and a carbon-containing compound such as methane, or the hydrogen may be present in compound form, as in the system dimethylhydrazine, nitrogen, and titanium tetrachloride. Alternatively, the necessary reactive constituents for forming the metal carbonitride coating may be contained in a single compound, such as tetrakis (dimethylamino) titanium.

United States Patent Wakefield et al.

[54] COATING FOR ASSEMBLY OF PARTS [72] Inventors: Gene F. Wakefield; Carl D. Reedy, Jr.,

both of Richardson; John A. Bloom, Dal- 211 App1.No.: 788,326

[52] US. Cl ..415/200, 23/359, 29/460, 29/487,117/46 CG, 117/106 R, 117/106 C, 1l7/DlG. 10, 416/213, 416/224, 416/241 [51] Int. Cl. ..B23k 31/02, B23p 3/00, C230 11/08 [58] Field ofSearch ..1 17/106 D, 106 C, 106,46 CG; 29/487, 460; 260/4295; 23/359; 416/224, 241; 415/200 [56] References Cited UNITED STATES PATENTS 2,755,542 7/1956 Boegehold ..29/460 3,356,618 12/1967 Rich etal.... ..117/106DX 3,432,330 3/1969 Diefendorf ..117/46 CG F ORElGN PATENTS OR APPLICATIONS 95,792 7/1960 Czechoslovakia ..1 17/106 C 622,652 5/1949 Great Britain ..29/487 [151 3,637,320 51 'Jan.25,1972

7 OTHER PUBLICATIONS Moers, K. Partial Translation of Article in Zeitschrift fuer Anorganische und Allgemeine Chemie, vol. 198 (1931) pp. 260- 261.

7 Primary Examiner-Ralph S. Kendall Assistant Examiner-J. R. Batten, Jr. Attorney-Samuels M. Mims, Jr., James 0. Dixon, Andrew M. Hassell, Harold Levine, Melvin Sharp and John M. Harrison [5 7] ABSTRACT Metal carbonitride coatings are deposited on assemblies, the

parts of which are connected by an adherent material by first heating a selected assembly, including the adherent material, and subsequently contacting the assembly with a gaseous stream which will yield reactive hydrogen, nitrogen, carbon, and a selected metal, upon contact with the heated assembly. The gaseous stream may, for example, contain hydrogen, nitrogen, titanium tetrachloride, and a carbon-containing compound such as methane, or the hydrogen may be present in compound form, as in the system dimethylhydrazine, nitrogen, and titanium tetrachloride. Alternatively, the necessary reactive constituents for forming the metal carbonitride coating may be contained in a single compound, such as tetrakis (dimethylamino) titanium.

34 Claims, No Drawings material,

dust, etc. Development of erosion and corrosion resistance in such an application requires not only that the vanes and holding ring be provided with suitable protective coating, but also the brazed or welded area which connects them.

In the past, similar problems have been approached by utilizing coatings such as titanium carbide, which have been applied to a substrate such as metal by exposure of the surface of the metal usually elevated to a temperature between 900 and l,200 C. and reacted to form titanium carbide, which adhered to the surface of the metal. The hydrogen chloride and 2,962,388, and the description of equipment suitable for applying hard, dense coatings may be found in'U.S. Pat. No. 2,884,894.

One of the problems frequently encountered in coating a metal with titanium carbide at temperatures between 900 and l,200 C. is the loss of temper in the metal. It may be generally stated that metals, and in particular steel, or metals such as titanium alloys, are hardened by first elevating the metal to about l,000 C. or greater, and then quickly quenching it. After quenching, the metal is tempered by elevating the temperature to about 500 to 600 C., thus reducing brittleness and imparting toughness. If a hardened and tempered metal is then reheated to a temperature between 900 and 1,200 C. to permit application of a titanium carbide, the hardness and temper during the reheating process. If, after application of the coating, the metal is quenched to again achieve hardness, the coating may be damaged, as the metal will change in size during the quenching process. This size change can rupture the coating, create roughness therein, or from the surface of the metal. Not only is the integrity of the coating damaged, but the metal does not provide as tough a support, thereby necessitating that the coating be thicker to withstand the forces to which it may be subjected.

Another problem which is particularly associated with coating assembled components is the difficulty of achieving good adherence between the coating material and the braze, weld, or other adherent material joining the assembled parts. This difficulty is magnified when coating processes which involve interdiffusion of the coating constituents and the substrate material are utilized. since these processes tend to result in a coating of different composition on various areas of the substrate. This problem is particularly acute with regard to the point of attachment between the component parts, whether the connective means be a braze, weld, or other adhering material. Further, when materials having a widely varying composition are used in the assembly, for example, a braze connecting stainless steel parts,.a diffusion rate problem is coating of a hard material, such ascoating for assembled component 2 frequently encountered in the coating process. For example, the rate of diffusion of the coating constituents into a braze surface is much difierent from that characteristic of the stainless steel surface, and nonuniform coatings may result from such a diffusion imbalance, which can lead to pitting and spot corrosion under severe service conditions.

In accordance with this invention, it has been found that a deposition according to the process of this invention permits uniform coating of the assembly, including the connecting areas, regardless of the chemical composition of the respective parts and connecting material. The metal carbonitride coating provides an adherent, hard erosionand corrosion-resistant surface which substantially improves the performance and service life of the assembly upon which it is deposited.

Accordingly, an object of this invention is to provide an improved method for coating and enhancing the surface characteristics of substantially any assembly of components or parts.

Another object of the invention is to provide an adherent parts which is hard, dense, uniform, and oxygen and erosion resistant.

Still another object of this invention is to provide a novel, hard, adherent, and erosion-resistant coating which can be applied to metal assemblies at relatively low temperatures to thereby avoid loss of temper in the metals or alloys of which the respective members of the assemblies are composed.

A further object of the invention is to provide a process for coating an assembly of parts at a temperature above the melting point of the material used to bond the parts in the assembly together.

In accordance with a broad embodiment of this invention, there is provided a method for coating an assembly of parts with a metal-carbon-nitrogen compound at least some of the parts being connected by an adherent material capable of being softened in the assembly, which consists of the following steps: first, softening the adherent material and secondly, contacting the assembly with a gaseous stream containing carbon, nitrogen, and an element such as boron, silicon, and the transition metals of Groups IVB, VB, and VIB of the Periodic Chart, under conditions to yield the carbon, nitrogen, and the element in the reactive state and permit interaction between these constituents to form the desired compound.

The process of this invention is characterized by convenience in that a solid solution metal carbonitride coating can be applied at either low or high temperatures. For example, low-temperature deposition, according to the invention, will permit application of a perature of the reaction materials used to effect the coating.

Thus, in a preferred aspect of the invention, the assembly is I heated to a temperature to or above the softening point of the particular adherent material used to connect the parts in the assembly before the assembly is contactedv with the gaseous deposition stream.

As above noted, the process of the invention can be utilized to coat substantially any assembly of component parts utilizing essentially any joining material which is capable of being softened and subsequently hardened to maintain necessary structural rigidity -of the parts. For example, the

process is easily adaptable to coating parts connected by a braze, which may be an alloy or other combination of metals, as the situation dictates, at temperatures above the softening temperature of the alloy or metal. Further, welded components may also be coated, and in a preferred aspect of the invention, the material used to connect the parts of an assembly having a preselected configuration is an alloy, braze or a pure metal, as in a weld, for example.

As heretofore noted, in its broadest aspects, the invention can be practiced by utilizing a gaseous reactant stream containing a source of carbon, which may be a specific hydrocarbon or combination of hydrocarbons, a specified metal, and nitrogen. In a more preferred aspect of the invention, the vaporous stream which is passed over the heated assembly generally contains molecular hydrogen, a carbon-containing compound or mixture of such compounds, which readily decomposes within a specified temperature range, a metalcontaining compound which also decomposes when exposed to heat, molecular nitrogen, and/or a heat-decomposable nitrogen-containing compound. Alternatively, the nitrogen and carbon can be supplied from a single compound containing both nitrogen and carbon, which readily decomposes at a selected decomposition temperature.

Suitable metal-containing reactant compounds which may be used in the invention include metal halides. A preferred group of metal halides is represented by the generic formula Me(x),,, where n is a valence of Me; x is a halogen, e.g., fluorine, chlorine, bromine, and iodine; and Me is selected from silicon, boron, and the transition metals in Groups IVB, VB, and VIB of the Periodic Chart as set forth on page 8-2 of the Handbook of Chemistry and Physics, Chemical Rubber Company, 45th edition (1964). Generally, the transition metal tetrahalides, such as titanium tetrachloride or bromide, are most preferred. However, the transition metal dihalides and trihalides can be useful in some applications, particularly where it is desired to utilize the higher-temperature coating operations or to limit the amount of product hydrogen chloride evolved.

Suitable carbon-containing reactant compounds include cyclic and acyclic hydrocarbons having up to about 18 carbon atoms which readily decompose at elevated temperatures. Exemplary are paraffins, such as methane, ethane, propane, butane, pentane, decane, penta-decane, octa-decane, and aromatics such as benzene and halogen-substitute derivatives thereof, such as chlorobenzene, dichlorobenzene, dibromobenzene, and the like. Natural gas is a particularly preferred source of carbon, since it contains a variety of hydrocarbons and is readily available.

Thus, inanother preferred embodiment of the invention, the gaseous reactant stream contains hydrogen, nitrogen, a hydrocarbon or mixture of hydrocarbons, and a halide of a metal of the classes, heretofore identified. More preferably, the hydrocarbon is natural gas and the metalhalide is titanium tetrachloride, although it will be recognized that other readily available hydrocarbons such as propane, along with the titanium tetrachloride metal halide may also be conveniently utilized. Thus, a most preferred aspect of this embodiment of the invention is the use of titanium tetrachloride, in conjunction with natural gas or other hydrocarbons, as the source of carbon, in coating an assembly of parts wherein these parts are joined by an alloy, braze or metal.

Other carbon-containing compounds which may be utilized to effectively supply the carbon and nitrogen'for the .coating reaction, as well as the hydrogen as a necessary reducing agent for the metal halides, include the following:

hydrazine and a carbon-containing compound (I) wherein R, is selected from hydrogen and cyclic and acyclic hydrocarbon radicals having from one to 18 carbon atoms such as, for example, alkyl, cycloalkyl, aryl, aralkyl, and including the amino-substituted derivatives thereof, provided at least one R, group is one of said hydrocarbon radicals; and

wherein R is selected from cyclic and acyclic aliphatic hydrocarbon radicals having from one to 18 carbon atoms including the aromatic and amino-substituted derivatives thereof.

The easily activated carbon-containing compounds that can be used along with hydrazine include hydrocarbons having up to about 18 carbon atoms such as, for example, methane, ethane, propanes, butanes, pentanes, decanes, octadecanes and mixtures thereof, and aromatics such as benzene and halogen-substituted derivatives thereof. Additionally, nitrogen-containing hydrocarbons can be used such as alkyl amines, pyridine, and the compounds identified by generic vention where an assembly of parts is coated with a metal-carbon-nitrogen compound, the parts being connected by an adherent material capable of being softened and the metal in the coating being selected from silicon, boron, and the transition metals in Groups IVB, VB, and W8 of the Periodic Chart, the assembly is preferably heated and thereafter contacted with a stream of vaporous reactants which include two compounds, the first of which is a metal halide and the second is a carbonand nitrogen-containing compound. The metal halide preferably has the general formula Me(x),, where x is a halogen, n is the valence of Me, and Me is selected from the metals above noted. The carbon-nitrogen compound is preferably one of the above noted reactant compositions in groups (ID-(VI).

In another preferred aspect of this particular embodiment of the invention, the metal halide is preferably a metal chloride and more preferably, a titanium chloride. in a most preferred combination, .the vaporous reactant stream contains titanium tetrachloride and 1,1-dimethylhydrazine or, in the altemative, hydrazine and a hydrocarbon, along with hydrogen and/or nitrogen as a carrier gas.

As heretofore noted, it is preferable to utilize an alloy, braze or metal as the connecting material attaching the parts in a selected assembly, and it is further preferable to heat the assembly to a temperature at which the alloy or metal will soften and where the reactant compounds utilized to coat the assembly will disassociate. Under these conditions, it is preferred in the invention to utilize a metal halide and carbonnitrogen compound of groups (l)(Vl), above noted, in the coating vaporous stream. As in previous embodiments, it is also preferred that the metal halide be a metal chloride, for example, titanium chloride, and more preferably, that the reactant stream contain a nitrogen carrier gas, titanium tetrachloride, and t,l-dimethylhydrazine or, instead of the last compound, hydrazine and a hydrocarbon. Under conditions where the metal chloride and nitrogen-carbon compounds exemplified by groups (I)(VI) are used as in the above embodiments of the invention, it is preferred that the parts of the assembly be connected by a braze containing by weight from about 53 to about 55 percent silver, from about- 39 to about 41 percent copper, from about 4 to about 6 pernitrogen-containing preferably ethylene, pyridine, or trimethylamine. Under these conditions, the metal halide is fore,

ethylene, pyridine, or trimethylamine; and the adherent material connecting the parts to the assembly is an alloy, braze or metal. In a mostpreferred embodiment of the invention, a solid-solution layer of titanium carbonitride is vapor-deposited on an assembly, the parts of which are connected by a braze, by first heating perature to which the assembly is heated is range offrom about 700 to about 1,200 C.

about l,200 C. or higher.

which meet these criteria are represented by the formula An even more preferred ment of the invention are compounds of the above-identified um, tetrakis (diethylamino) titanium, tetrakis (dipentylamin'o) titanium, tetrakis (dioctylamino) titanium, tetrakis (diphenylamino) titanium, and the like.

Accordingly, in a preferred embodiment of the invention, an assembly of parts is coated with a metal-carbon-nitrogen material in the assembly is an alloy, braze, or metal and the contacting temperature is above the melting temperature of this alloy, braze, or metal. In another aspect of this embodiment of the invention, the organic compound may be dispersed within a carrier gas such as nitrogen, hydrogen, or mixtures thereof, and in a most-preferred embodiment, the organic compound has the generic fonnula [(R) N],.Me, where Me is an element of the group boron, silicon, and the transition metals of the Groups IVB, VB, and VlB of the Periodic Chart; n is a valence of Me; and R is selected from hydrogen and hydrocarbon radicals each having from one to about 18 carbon atoms, provided one R group is at least one of the hydrocarbon radicals.

Where such a compound is used in the invention, a preferred method of operation is to select the adherent material for connecting the parts of the assembly such that the softening thereof may be effected below the decomposition temperature of the organic compound. In this manner, it may be assured that the adhering material is in a softened or melted state before the selected reactive coating compound is decomposed to yield the desired metal carbonitride coating. Particular compounds which have been efiective in this aspect of the invention are tetrakis (dimethylamino) titanium, tetrakis (diethylamino) titanium, and tetrakis (diphenylamino) titanium. Accordingly, it is preferred to use one of these compounds in conjunction with an adherent material such as an alloy, braze, or metal in the assembly in a coating environment above the melting temperature of the alloy, braze, or metal.

Accordingly, in a most-preferred embodiment of the invention, there is provided a method of coating an assembly of parts with a solid-solution layer of titanium carbonitride, at least some of these parts being connected in the assembly by a braze, which includes first heating the assembly to a temperature above the melting temperature of the braze, and subsequently contacting the assembly at this temperature with a gaseous stream containing hydrogen and one or more of the organic compounds, tetrakis (dimethylamino) titanium, tetrakis (diethylamino) titanium, or tetrakis (diphenylamino) titanium. More particularly, the braze is preferably one which contains by weight from about 53 to about 55 percent silver, from about 39 to about 41 percent nickel, and the temperature at which the reaction should be effected is within the range of from about 700 to about l,200 C.

From a consideration of the above-enumerated embodiments of the invention, it is obvious that there can be manufactured by operation of the process described above, an article which is made up of an assembly of parts, at least some of which are connected by a suitable adherent material, the assembly having a preselected configuration and having a homogeneous solid solution of a carbonitride of an element selected from silicon, boron, and the transition metals of Groups IVB, VB, and VIB of the Periodic Chart formed on the surface of the parts of the assembly and on the surface of, as well as interspersed in, the surface of the adherent material. More particularly, the assembly may be made up of parts which are preferably connected by an alloy, braze, or metal (as in a weld, for example), and the carbonitride coating is preferably titanium carbonitride. Further, the adherent material utilized is most preferably a braze containing by weight from about 53 to about 55 percent silver, from about 39 to about 4i percent copper, from about 4 to about 6 percent zinc, and from about one-half to about 1% percent nickel, and the assembly most frequently utilized is a stainless steel vane sector brazed into; holding rings for jet engine utilization. Further, the titariium carbonitride coating is preferably from about one-half to about 1% mils thick.

The invention can perhaps be best understood by reference to the following illustrative examples which are not intended to be unduly limitative of the invention.

h. EXAMPLE A jet engine vane sector having an AM 355 stainless steel vane and a 309 stainless steel holding band were brazed together with a silver-copper braze having the following composition: silver 54:! percent, copper 40:1 percent, zinc 510.5 percent, and nickel 1:0.25 percent. ,This braze complies with aerospace material specification AMS.4772A and ASTM specification ASTM-260. The softening point of this braze is about 718 C. and the melting temperature is about 856 C.

A reactant vapor stream of hydrogen, nitrogen, titanium tetrachloride and natural gas was then generated, the natural gas having the following composition:

Constituent Amount (Weight Percent) Methane 87-91 Ethane 6.18 Propane 2.76 N-Butane 0.88 lsobutane 0.30 lsopentane 0. l 7 Pentane 0.2] Nitrogen L19 Carbon Dioxide 0.118 Helium 0.04 Hydrogen Sulfide 2 p.p.m.

Ethyl Mercaptan 0.6 lbJmillion/cu. ft.

The engine vane sector and holding band were then placed within a reactor and a vacuum was pulled on the reaction chamber to exhaust the air. The reactor was then filled with hydrogen and the vane assembly heated to 900 C. After the assembly reached reaction temperature, the gaseous stream containing the reactants was passed thereover for a period of 3 hours at the following rates: hydrogenl 50 liters per minute, nitrogen23 liters per minute, TiCl,2.5 milliliters per minute, natural gas-21 liters per minute. The vane sector and holding band assembly were then taken from the reactor, allowed to cool, and were found to have a very hard, solid solution of titanium carbonitride deposited over the multimaterial components. Close inspection and photomicrographs of a cross section of the assembly through the brazed area confirms that the coating adhered well to all component parts, including the brazed material. Erosion and corrosion tests showed that the coating is highly protective to the materials in question, including the braze.

It is significant that the invention is characterized by flexibility in that it can be carried out in commercially available equipment. It is preferred that the assembly to be coated be suspended in a reaction chamber and heated to a temperature at which the vaporous reactant material selected will decompose when contacted therewith. Thus, the temperature to which the substrate may be heated will depend upon the particular reactants employed, but will generally vary within the temperature range of about 400 to about 1,200 C. For example, a temperature of about 400 C. can be utilized with a vaporous reaction system of titanium tetrachloride, triamine ethylene, hydrogen, and nitrogen; and a temperature of about 900 C. or higher may be used for the system titanium tetrachloride, natural gas, hydrogen, and nitrogen. After the substrate is properly heated, a vaporous stream containing the selected reactant compound or compounds is passed directly over the surface of the substrate, whereby deposition of the metallic carbonitride on the substrate occurs. The atomic ratios between the metal and the reactive nitrogen and carbon within the vaporous reactant stream are generally not critical and can be varied with both the type and quantities of the particular reactants utilized.

The metal carbonitride coatings applied by the method of the present invention are solid solution materials having a selected metal, carbon, and nitrogen within a single-phase crystal lattice. The hardness of conventional transition metal carbide structures are believed to be derived from the strong bonding forces and difficulty of dislocation movement through the structure. The material titanium carbide is characterized by metallic, ionic, and covalent atomic bonding arrangements. The metallic-type bonds generally have a very slight effect on the molecule, as indicated from the small number of mobile charge carriers present. The ionic contribution is significant, reportedly approximately 1.3 electrons transferred from the 2? states of carbon to the 3D states of titanium. The presence of covalence (directed orbital) bonds between both nearest and the next nearest neighbors has a major influence on the properties, hardness, brittleness, and strength of the material.

The metal carbonitride solutions have crystal structures very similar to the transition metal carbides, but they differ from these materials in that they can be tailored to exhibit optimized properties by procedures calculated to influence the type and magnitude of the bonds formed. The capability of tailoring the bonding, and hence the properties of these carbonitride structures, can be realized from utilization of the extra valence electron possessed by nitrogen over that available with the element carbon, which is also present in the crystal lattice.

As heretofore observed, various types of materials may be coated by the process of the present invention, including ferrous metals; titanium; ceramic materials; and refractory metals, such as tungsten, molybdenum, niobium, and tantalum.

From a consideration of the above embodiments, it will be appreciated that the sources of the nitrogen, carbon, and the appropriate metal may take various forms, as exemplified by compounds having all three elements in their molecular structure, as well as compounds having less than all these elements, in combination with either the missing element itself or another compound containing the missing element. It is only necessary that these elements be present in a reactable state when they contact the surface of the assembly to be coated under appropriate coating conditions. Further, the source of carbon need not be pure as evidenced by the example heretofore noted, in order for good coatings to be realized.

The carbon, nitrogen, and metal components can be brought to the reactive state by any suitable technique. As heretofore mentioned, a vaporous reactant stream containing the three components can be passed over a heated assembly to thereby yield the three components in the reactive or activated state. Additionally, it is within the scope of this invention to utilize any other available technique which may yield the three components in the activated state within the vaporous reactant stream which is passed over the substrate.

While rather specific terms have been used in describing various embodiments of the present invention, these terms are not intended nor should they be implied as a limitation upon the invention.

What is claimed is:

1. A method for coating an assembly of parts with an element carbon-nitrogen compound, at least some of said parts being connected by an adherent material comprising an alloy, braze or metal, which comprises:

a. softening said adherent material; and

b. contacting said assembly with a gaseous stream containing carbon, nitrogen, and an element selected from the group boron, silicon, and the transition metals of Groups lVB, VB, and VlB of the Periodic Chart, under conditions to yield said carbon, nitrogen, and element in the reactive state and permit reaction thereof to form said compound.

2. The method of claim 1, wherein said assembly is heated to a temperature at least above the softening point of said adherent material before being contacted with said gaseous stream.

3. The method of claim 2, wherein said gaseous stream contains hydrogen, at least one hydrocarbon, and a halide of said element.

4. The method of claim 3, chlorobenzene and said halide is wherein said hydrocarbon is titanium tetrachloride.

5. The method of claim 3, wherein said hydrocarbon is natural gas and said halide is titanium tetrachloride.

6. The method of claim 3, wherein:

a. said halide is titanium tetrachloride; and

b. said at least one hydrocarbon is selected from the group propane, chlorobenzene and natural gas.

7. The method of claim 2, wherein said gaseous stream contains hydrogen, a halide of said element, and a nitrogen-containing hydrocarbon.

8. The method of claim 7, wherein said halide is titanium tetrachloride and said nitrogen-containing hydrocarbon is diamine ethylene.

9. The method of claim 7, wherein said halide is titanium tetrachloride and said nitrogen-containing hydrocarbon is pyridine. I

10. The method of claim 7, wherein said halide is titanium tetrachloride and said nitrogen-containing hydrocarbon is trimethylamine.

l l. The method of claim 7, wherein:

a. said halide is titanium tetrachloride; and

b. said nitrogen-containing hydrocarbon is selected from the group diamine ethylene, pyridine, and trimethylamine.

12. The method of claim 1, wherein said carbon, nitrogen, and element are constituents of a vaporous, hydrogen-containing organic compound capable of being decomposed to yield said carbon, nitrogen, and element in the reactive state to form said element-carbon-nitrogen compound.

13. The method of claim 12, wherein:

said contacting is effected at a temperature above the melting temperature of said alloy, braze, or metal.

14. The method of claim 12, wherein said organic compound is dispersed within a carrier gas selected from nitrogen, hydrogen, and mixtures thereof.

15. The method of claim 12, wherein said organic compound has the generic formula [(R) N],,Me wherein: Me is an element of the group boron, silicon and the transition metals of groups IVB, VB and VIB of the Periodic Chart; n is a valence of Me; and R is selected from hydrogen and hydrocarbon radicals each having from one to about 18 carbon atoms, provided at least one R group is at least one of said hydrocarbon radicals.

16. The method of claim 15, wherein said softening is effected below the decomposition temperature of said organic compound.

17. The method of claim 15, pound is tetrakis (dimethylamino) titanium.

18. The method of claim 15, wherein said organic compound is tetrakis (diethylamino) titanium.

19. The method of claim 15, wherein said organic compound is tetrakis (diphenylamino) titanium.

20. The method of claim 15, wherein:

a. said organic compound is selected from the group tetrakis (dimethylamino) titanium, tetrakis (diethylamino) titanium, and tetrakis (diphenylamino) titanium; and

b. said contacting is effected at a temperature above the melting temperature of said alloy, braze, or metal.

21. A method of coating an assembly of parts with a solid solution layer of titanium carbonitride, at least some of said parts being connected by a braze, which comprises:

a. heating said assembly to a temperature above the melting temperature of said braze; and

b. contacting said assembly with a gaseous stream containing titanium tetrachloride, natural gas, hydrogen, and nitrogen to effect deposition of said titanium carbonitride on said assembly.

22. The method ofclaim 21, wherein:

a. said braze contains by weight from about 53 to about 55 percent silver, from about 39 to about 41 percent copper, from about 4 to about 6 percent zinc, and from about one-halfto about 1% percent nickel; and

b. said temperature is within the range offrom about 700 to about l,200 C.

wherein said organic com- 23. A method of coating an assembly of parts with a solid solution layer of titanium carbonitride, at least some of said parts being connected by a braze, which comprises:

a. heating said assembly to a temperature above the melting temperature of said braze; and

b. contacting said assembly at said temperature with a gaseous stream containing hydrogen and an organic compound selected from the group tetrakis (dimethylamino) titanium, tetrakis (diethylamino) titanium, and tetrakis (diphenylamino) titanium, said organic compound being dispersed within said hydrogen.

24. The method of claim 23, wherein:

a. said braze contains by weight from about 53 to about 55 percent silver, from about 39 to about 41 percent copper, from about 4 to about 6 percent zinc, and from about one-half to about 1% percent nickel; and

b. said temperature is within the range of from about 400 to about l,200 C.

25. A method of producing a carbonitride coating on an assembly of parts, at least some of said parts being connected by an alloy braze or metal, with vaporous reactant compounds comprising:

a. heating said assembly to at least a temperature at which said alloy, braze, or metal will soften and said reactant compounds will disassociate; and

b. contacting said assembly in the absence of substantial molecular hydrogen with a vaporous stream consisting essentially of a carrier gas and reactant compounds selected from (1) a halide having the general formula Me(x),,, wherein x is a halogen, n is a valence of Me, and Me is selected from silicon, boron, and transition metals in Groups IVB, VB, and VIB of the Periodic Chart, and (2) reactants selected from:

hydrazine and a carbon-containing compound (I) wherein R, is selected from hydrogen and cyclic or acyclic hydrocarbon radicals each having from one to about 18 carbon atoms including the amino-substituted derivatives thereof, provided at least one R, group is one of said hydrocarbon radicals, and wherein R is selected from cyclic and acyclic aliphatic hydrocarbon radicals each having from one to about 18 carbon atoms including the aromatic and aminosubstituted derivatives thereof.

26. The method of claim 25, wherein said halide is a chloride.

27. The method of claim 26, titanium chloride.

28. The method of claim 27, wherein said reactant stream consists essentially of a nitrogen carrier gas, titanium tetrachloride, and l, l -dimethyihydrazine.

29. The method of claim 27, wherein said vaporous stream consists essentially of a nitrogen carrier gas, titanium tetrachloride, hydrazine, and at least one hydrocarbon.

30. The method of claim 25, wherein:

a. said at least some of said parts are connected by a braze containing by weight from about 53 to about 55 percent silver, from about 39 to about 41 percent copper, from about 4 to about 6 percent zinc, and from about one-half to about PA percent nickel; and

wherein said chloride is a b. said temperature is within the range of from about 400 to about i,200 C.

31 An article comprising:

a. an assembly of parts, at least some of said parts being connected by an adherent material comprising an alloy, braze or metal, said assembly having a preselected configuration; and

b. a homogeneous solid solution of a carbonitride of an element selected from silicon, boron, and the transition metals of Groups lVB, VB, and VIB of the Periodic Chart, formed on the surface of said parts and on the surface of, and interspersed in, the surface of said adherent material.

bonitride is from about one-half to about 1% mils thick. 

2. The method of claim 1, wherein said assembly is heated to a temperature at least above the softening point of said adherent material before being contacted with said gaseous stream.
 3. The method of claim 2, wherein said gaseous stream contains hydrogen, at least one hydrocarbon, and a halide of said element.
 4. The method of claim 3, wherein said hydrocarbon is chlorobenzene and said halide is titanium tetrachloride.
 5. The method of claim 3, wherein said hydrocarbon is natural gas and said halide is titanium tetrachloride.
 6. The method of claim 3, wherein: a. said halide is titanium tetrachloride; and b. said at least one hydrocarbon is selected from the group propane, chlorobenzene and natural gas.
 7. The method of claim 2, wherein said gaseous stream contains hydrogen, a halide of said element, and a nitrogen-containing hydrocarbon.
 8. The method of claim 7, wherein said halide is titanium tetrachloride and said nitrogen-containing hydrocarbon is diamine ethylene.
 9. The method of claim 7, wherein said halide is titanium tetrachloride and said nitrogen-containing hydrocarbon is pyridiNe.
 10. The method of claim 7, wherein said halide is titanium tetrachloride and said nitrogen-containing hydrocarbon is trimethylamine.
 11. The method of claim 7, wherein: a. said halide is titanium tetrachloride; and b. said nitrogen-containing hydrocarbon is selected from the group diamine ethylene, pyridine, and trimethylamine.
 12. The method of claim 1, wherein said carbon, nitrogen, and element are constituents of a vaporous, hydrogen-containing organic compound capable of being decomposed to yield said carbon, nitrogen, and element in the reactive state to form said element-carbon-nitrogen compound.
 13. The method of claim 12, wherein: said contacting is effected at a temperature above the melting temperature of said alloy, braze, or metal.
 14. The method of claim 12, wherein said organic compound is dispersed within a carrier gas selected from nitrogen, hydrogen, and mixtures thereof.
 15. The method of claim 12, wherein said organic compound has the generic formula ((R)2N)nMe wherein: Me is an element of the group boron, silicon and the transition metals of groups IVB, VB and VIB of the Periodic Chart; n is a valence of Me; and R is selected from hydrogen and hydrocarbon radicals each having from one to about 18 carbon atoms, provided at least one R group is at least one of said hydrocarbon radicals.
 16. The method of claim 15, wherein said softening is effected below the decomposition temperature of said organic compound.
 17. The method of claim 15, wherein said organic compound is tetrakis (dimethylamino) titanium.
 18. The method of claim 15, wherein said organic compound is tetrakis (diethylamino) titanium.
 19. The method of claim 15, wherein said organic compound is tetrakis (diphenylamino) titanium.
 20. The method of claim 15, wherein: a. said organic compound is selected from the group tetrakis (dimethylamino) titanium, tetrakis (diethylamino) titanium, and tetrakis (diphenylamino) titanium; and b. said contacting is effected at a temperature above the melting temperature of said alloy, braze, or metal.
 21. A method of coating an assembly of parts with a solid solution layer of titanium carbonitride, at least some of said parts being connected by a braze, which comprises: a. heating said assembly to a temperature above the melting temperature of said braze; and b. contacting said assembly with a gaseous stream containing titanium tetrachloride, natural gas, hydrogen, and nitrogen to effect deposition of said titanium carbonitride on said assembly.
 22. The method of claim 21, wherein: a. said braze contains by weight from about 53 to about 55 percent silver, from about 39 to about 41 percent copper, from about 4 to about 6 percent zinc, and from about one-half to about 1 1/2 percent nickel; and b. said temperature is within the range of from about 700* to about 1,200* C.
 23. A method of coating an assembly of parts with a solid solution layer of titanium carbonitride, at least some of said parts being connected by a braze, which comprises: a. heating said assembly to a temperature above the melting temperature of said braze; and b. contacting said assembly at said temperature with a gaseous stream containing hydrogen and an organic compound selected from the group tetrakis (dimethylamino) titanium, tetrakis (diethylamino) titanium, and tetrakis (diphenylamino) titanium, said organic compound being dispersed within said hydrogen.
 24. The method of claim 23, wherein: a. said braze contains by weight from about 53 to about 55 percent silver, from about 39 to about 41 percent copper, from about 4 to about 6 percent zinc, and from about one-half to about 1 1/2 percent nickel; and b. said temperature is within the range of from about 400* to about 1,200* C.
 25. A method of producing a carbonitride coating on an assembly of parts, at least some of said parts being connected by an alloy braze or metal, with vaporous reactant compounds comprising: a. heating said assembly to at least a temperature at which said alloy, braze, or metal will soften and said reactant compounds will disassociate; and b. contacting said assembly in the absence of substantial molecular hydrogen with a vaporous stream consisting essentially of a carrier gas and reactant compounds selected from (1) a halide having the general formula Me(x)n, wherein x is a halogen, n is a valence of Me, and Me is selected from silicon, boron, and transition metals in Groups IVB, VB, and VIB of the Periodic Chart, and (2) reactants selected from:
 26. The method of claim 25, wherein said halide is a chloride.
 27. The method of claim 26, wherein said chloride is a titanium chloride.
 28. The method of claim 27, wherein said reactant stream consists essentially of a nitrogen carrier gas, titanium tetrachloride, and 1,1-dimethylhydrazine.
 29. The method of claim 27, wherein said vaporous stream consists essentially of a nitrogen carrier gas, titanium tetrachloride, hydrazine, and at least one hydrocarbon.
 30. The method of claim 25, wherein: a. said at least some of said parts are connected by a braze containing by weight from about 53 to about 55 percent silver, from about 39 to about 41 percent copper, from about 4 to about 6 percent zinc, and from about one-half to about 1 1/2 percent nickel; and b. said temperature is within the range of from about 400* to about 1,200* C.
 31. An article comprising: a. an assembly of parts, at least some of said parts being connected by an adherent material comprising an alloy, braze or metal, said assembly having a preselected configuration; and b. a homogeneous solid solution of a carbonitride of an element selected from silicon, boron, and the transition metals of Groups IVB, VB, and VIB of the Periodic Chart, formed on the surface of said parts and on the surface of, and interspersed in, the surface of said adherent material.
 32. The article of claim 31, wherein: said carbonitride is titanium carbonitride.
 33. The article of claim 32, wherein: a. said adherent material is a braze containing by weight from about 53 to about 55 percent silver, from about 39 to about 41 percent copper, from about 4 to about 6 percent zinc, and from about one-half to about 1 1/2 percent nickel; and b. said assembly consists of stainless steel vane sectors brazed into holding rings in jet engines.
 34. The article of claim 33, wherein said titanium carbonitride is from about one-half to about 1 1/2 mils thick. 